CONJUNCTIVE USE

Introduction

PREVENTIVE/REMEDIAL MEASURES

Conjunctive Use of Surface and Ground water

STUDIES ON CONJUNCTIVE USE OF SURFACE WATER AND GROUND WATER RESOURCES IN A PART OF SHARDA SAHAYAK IRRIGATION PROJECT, U.P.

CONJUNCTIVE WATER USE MECHANISM

Introduction

             Ever since the appearance of man on the Earth, he has been endeavouring to utilize maximum quantity of water to meet day to day requirements from all possible sources without understanding the adverse impact of indiscriminate use of resources. Overutilization of surface water, especially in the upper and middle reaches in most of the canal commands, has given rise to deleterious effects, viz. (i) Water Logging, (ii) Salinization/alkalinization of soils resulting in general degradation of arable land and over all deterioration in crop productivity and (iii) deficit water supply at the tail ends. The factors as poor drainage properties of soil, low gradient and unlined channels (incurring huge seepage losses), have added to the water-logging problem in the command area. The conjunctive use of surface and ground water offers the solution to a large extent to these problems.

              The planning for integrated and conjunctive use of surface and ground water resources calls for detailed investigations and studies regarding sub-soil conditions of the basin in respect of its storativity and transmissivity and its interaction with surface water as well as adjacent areas. For promotion of good crops, adequate and timely irrigation is essential, which may not be ensured by a single resource and warrants a judicious use of both surface and ground water resource.

PREVENTIVE/REMEDIAL MEASURES

1.It is suggested that before a surface water irrigation project is planned, the ground water regime of the area should be thoroughly understood.

2 Ground water Pumping The ground water pumping in the areas having rising trend should be such that the temporal fluctuations of water table should be below root zone of the plants. The pumping should not affect the yield of existing dugwells and shallow handpumps.

3 Farm Water Management

In the absence of proper farm water management for crops, the accumulation of water in low lying areas and its deep percolation down to ground water resulted in rise of water table. Initially the drainage of the command area and clearance of nalas should be taken on priority. The unplanned and unauthorized cultivation of crops like paddy and sugarcane must be minimized. The area where land remains submerged for most part of the year is suitable for crops like paddy with eucalyptus plantation on bunds and chak-roads.

4 Canal Seepage

Canal seepage can best be controlled by lining the canals. But since this is very costly affair it is recommended that the farmers should be made aware of planned and proper utilization of canal water so as to maintain the water level within 4 to 5 m bgl.

5. Control of Salinity

            Generally, the salinity due to water logging can be kept under control by keeping the water level at such a depth from where evaporation of water would not be possible. But the soil of the area already affected by salinization possesses saline matter. In such condition leaching by water is recommended. It will leach down the excess salts from the affected soil. This may be done by ponding and drying alternately. However, this method is not effective in the area where water table is very shallow and drainage is poor. In such areas horizontal drainage must be developed by giving priorities to existing nalas. The use of gypsum and green manure may improve the physical texture and structure of alkali soils.

6. Afforestation

            To control the rise of water table in water logged areas, afforestation along canals and field boundaries and in water logged area should be encouraged. For this, vegetation especially deep rooted and high water consuming trees should be planted for increased evapo-transpiration, e.g. Eucalyptus and Terminellia arjuna, etc.

7. Farmers’ Managed Irrigation System

            It is observed that the performance of Govt. Managed Irrigation Schemes (GMIS) has been very unsatisfactory and deteriorating. The reasons being inefficient machinery, poor functioning and irresponsive nature towards poor maintenance and operation, water distribution system and biased orientation of field staff. It is recommended to switch over from GMIS to FMIS (Farmers’ Managed Irrigation System) thus making farmers responsible to control and manage water from source to irrigation fields and also maintenance and operation of distribution system. This can be achieved by creating Farmers’ Water Users Organisation (WUO’s). This system has been successfully run in West Bengal and Bihar.

8. Fisheries Development

         This programme can be taken up in areas that are water logged throughout the year.

Conjunctive Use of Surface and Ground water

        The conjunctive water use mechanism should be evolved for the study area not only for scheduling of optimum use of water resources vis-à-vis demand but also to tackle the problem of rising water levels and spread of salt infested land- the Usar. A suitable plan for controlling the problem of rising water levels should be evolved using mathematical modeling techniques, so as to simulate hydrogeological situations and generate various future scenarios and accordingly suggesting plans to cope up with it. Since the canal water is cheaper it is being over used causing water logging problem. Hence the rate of canal water should be brought at par with the tubewell water to discourage the over-use.

STUDIES ON CONJUNCTIVE USE OF SURFACE WATER AND GROUND WATER RESOURCES IN A PART OF SHARDA SAHAYAK IRRIGATION PROJECT, U.P.

        Realising the importance of the conjunctive use surface and ground water in general and in the irrigation command in particular Govt. of India sanctioned one conjunctive use scheme namely - Sharda Sahayak, in Uttar Pradesh, to yield some fruitful solutions in form of analysis of the results and recommendations. During 1990-91 to 1994-95, the study was carried out by CGWB, Northern Region, Lucknow in Sai-Gomti doab, in central part of Sharda Sahayak command area. It lies in parts of Barabanki, Lucknow, Rae Bareli, Sultanpur, Pratapgarh and Jaunpur districts, covering an area of 8978 km2

This conjunctive use studies were under taken with following objectives:

        · Evaluation of water resources w.r.t. quantification of surface and ground water resources available in space and time so as to determine the water balance. ·

Identification of critical areas of water logging and soil salinity. ·

Matching demands of various sectors with the available water resources and to evolve a strategy to meet the projected demand of the future.

· Mathematical modeling studies to simulate hydrogeological situation, generation of various scenarios to evolve strategies for optimum development of ground water resources. ·

To evolve a suitable plan for controlling the problem of rising water levels by adopting the technique of conjunctive use of surface and ground water and proper drainage.

· To prepare sector/blockwise plans for development of ground water resource in conjunction with surface water based on mathematical model results.

· To test the sustainability of the present irrigation pattern w.r.t. Conjunctive use of water resources and suggest improvement for future. ·

To evaluate the economic aspect of ground water development plan w.r.t. cost benefit ration, internal rate of return and pay back period etc.

CONJUNCTIVE WATER USE MECHANISM

         Using the mathematical model and other studies the conjunctive water use mechanism has been evolved for the study area not only for scheduling of optimum use of water resources vis-à-vis demand but also to tackle the problem of rising water levels and soread of salt infested land, the Usar. It was felt that rescheduling of the operation of canal is required to be modified in accordance with the crop water requirement during Kharif and Rabi seasons in different blocks. An attempt was made to present simulated ‘work frame’ giving crop water requirement and proposed surface and ground water use pattern in time and space. To meet the proposed quantum of ground water draft, number of additional shallow tubewells needed was worked out with proper spacing between two structures. Blockwise withdrawal of ground water during Kharif and Rabi crop season for different cropping intensities of 153 and 200 percent have been worked out. The simulation studies have clearly indicated that the water levels in the larger part of the area would remain within desirable limits once the conjunctive water use strategy is implemented. Besides, immediate impact of this mechanism would be the reduction of water logged area and the one prone to water logging percent area from 52% to 27% within the first decade of the adoption of the scheme. The cash outflows and inflows have been calculated considering ‘Without Project’ situation along with payback period and with the average pay back period was calculated as 7.67 months and benefit cost ratio of ‘without project’ and ‘with project’ as 1.49 and 1.56 respectively. The internal rate of return (IRR) was computed 8.90 and 9.18% respectively.